Sulfate and Phosphate Displacement of Arsenic from Fly Ash Amended Soil
Author(s)
Qafoku, Nikolla P.
Kukier, Urszula
Sumner, Malcolm E.
Miller, William P.
Radcliffe, David E.
Advisor(s)
Editor(s)
Hatcher, Kathryn J.
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Abstract
Arsenic (As) is the biggest environment contaminant in most of the soils where fly ash is applied. As is usually not mobile and strongly adsorbed onto soil particles. However, in gypsum and phosphorus amended soils As may be much more mobile. A study in repacked columns with soil from Ap horizon was conducted to determine whether or not As becomes mobile when Ca(H₂PO₄)₂ and CaSO₄ are used as leaching solution, and to compare the competitive interactions between PO₄-AsO₄ and SO₄.-AsO₄. As concentration in leachate was approximately ten times greater when Ca(H₂PO₄)₂ was used to leach the columns as compare to CaSO₄. A concentration of 800 µg As L⁻¹
was found in this case, which is sixteen times the limit of 50 µg As L⁻¹ established by the EPA for groundwater. In fly ash the portion of arsenate non-specifically adsorbed is believed to be much lower than that of arsenate specifically adsorbed. Sulfate anions were able to displace only non-specifically adsorbed arsenate. However, the concentration of As in leaching solution was found to be within acceptable limits. Phosphate can compete with arsenate for all available adsorption sites, non-specific and specific.
Sponsor
Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, The University of Georgia, Georgia State University, Georgia Institute of Technology
Date
1997-03
Extent
Resource Type
Text
Resource Subtype
Proceedings